The invention relates to a commercial two part jacking system for lifting and supporting a corner of an automobile; particularly to an improved lift bridge that is securely fastened to the rear cover plate of a power unit or alternatively securely fastened to the forward ends of lift arms of the power unit. The inventor of the present invention is a pioneer of the two part jacking system and holds numerous patents for two part jacking systems, some of which are described below.
Briefly, the commercial two part jacking system consists of a mobile power unit and a set of separate mechanical jack stands. Examples of the two part jacking system and mobile power unit are described in detail in U.S. Pat. Nos. Re. 32,715; 4,589,630 and 6,986,503. Some examples of the jack stands are described in detail in U.S. Pat. Nos. 4,553,727; 5,110,089; 5,183,235 and 5,379,974. The stands are capable of being vertically extended and retracted from the garage floor or road surface and, when extended, can be locked in place at a desired position by a ratchet and pawl assembly. The power unit has a wheeled mobile chassis adapted to carry a plurality of the jack stands, and has a pair of lift arms adapted to mate with the outermost jack stand for placement and removal.
In use, the commercial mobile power unit is operated from its handle. It is maneuvered under a vehicle to place a jack stand in a desired location for lifting and supporting the vehicle. The power unit is activated from the handle, and the jack stand is then extended vertically to the desired height, thus lifting the vehicle on the stand. By operating the controls at the end of the handle, the operator can cause the power unit to disengage from the stand, and the stand will remain locked in its extended supporting position under the vehicle.
After the stand is raised and locked in place supporting the vehicle, or other load, in an elevated position, the power unit lift arms are lowered and the power unit is disengaged from the stand and pulled away, leaving the stand in position supporting the load. Another jack stand, carried within the chassis, is automatically transferred to the forward end the chassis for placement at another desired location of the vehicle or for use in lifting and supporting another vehicle.
To lower the vehicle and remove the stand, the power unit is maneuvered to re-engage with the stand. The engagement causes any existing jack stands carried within the chassis to be automatically transferred rearward within the chassis. By manually operating a control at the end of the handle, the operator can cause the power unit to re-engage with the stand, and to disengage the ratchet locking mechanism of the stand, and to lower the stand to its original position. The power unit remains engaged with the stand and can be pulled away from the vehicle with the stand carried within the chassis.
The original commercial power units were adapted to carry up to four jack stands within the chassis. Additional jack stands could be acquired to reload the power unit, so that a single power unit could be utilized to efficiently place and actuate numerous jack stands. It was found that many commercial users would utilize all of their available jack stands, and the power unit was thereafter useless until another jack stand was available to be extracted and reused. The present inventor developed a two position lift bridge (and also an automatic-slide-forward bridge) that adapted the power unit to function as a load-lifting jack to more fully utilize the power unit. This invention is illustrated in U.S. Pat. No. 6,779,780 entitled Lift Bridge For Use With a Power Unit and a Load Lifting Jack, along with several other patents related to additional features of the lifting system.
In the continuous development and manufacture of these lifting devices, unique improvements often result in additional inventions. As in the present invention, it was discovered during ship testing that in certain situations, the two-position lift bridge that was nested in the rear cover plate could become dislodged during shipping.
In view of the foregoing situation, it is an object of the present invention to provide an improved two-position lift bridge that can be securely fastened to the rear cover plate.
It is another object to provide an improved two-position lift bridge that can be securely fastened to the leveling pads on the forward ends of the lift arms of the power unit.